In a surgical method for femoral trochanteric fracture, an internal fixator referred to as a compression (dynamic) hip screw as shown in FIG. 1 is often used. The compression (dynamic) hip screw is constituted of a sleeve plate 1 and a lag screw 2. The sleeve plate 1 includes a sleeve 3 and a plate 4. The sleeve 3 has a substantially cylindrical shape. The plate 4 is to be secured to femoral diaphysis by screws. The lag screw 2 is configured to firmly hold a femoral head with a screw part thereof, and to slide within the sleeve 3. Thus, compression force is applied to fractured ends to promote bone union.
As shown in FIG. 2, an inner cortical bone 6 at the fracture site has the strongest bone strength in femoral trochanteric fracture (site) 5. The inner cortical bone 6 is the main part to receive a load. In addition, an inner lower part 8 of a femoral head has the densest and strongest bone quality in the cancellous bone of a femoral head 7.